For example, in a receiver that receives a weak radio wave of a millimeter wave band, a terahertz wave band or a like wave band, a low noise amplifier, a detector and so forth are required. A Schottky diode is used for the detector.
However, where the Schottky diode is used, it is difficult to obtain a sufficient detection characteristic in the proximity of a bias of 0 V.
Therefore, the inventor of the present invention has proposed to use a backward diode wherein a p-type GaAsSb layer and an n-type InGaAs layer are pn-joined in place of the Schottky diode in order to improve the detection characteristic.
It is to be noted that a technique is available wherein, in order to efficiently confine injection carriers in an active layer so that electrons and holes are re-coupled in a semiconductor light emitting device such as a semiconductor laser, a multiple superlattice structure is provided to increase the height of an energy barrier against electrons or holes. Further, a technique is available wherein, in a semiconductor light emitting device such as a semiconductor laser, a multiple quantum well structure portion or a multiple quantum barrier structure portion for controlling the advancement of minority carriers into a cladding layer is provided between the cladding layer and an active layer.